164 THE STRUCTURE AND LIFE OF BIRDS cHAP. 
to protect their legs from the formidable beaks among 
which they had to run the gauntlet. The Woodpecker 
pecks a hole in a tree in which to make his nest. His 
beak is the hammer with which the Nuthatch, swing- 
ing at the hips, cracks his nut. A Thrush may be 
seen picking up a snail and dashing it on a stone to 
break the shell. The beak is also used to preen the 
feathers, even a short-necked bird being able to bring 
it to bear on almost any part of his plumage. When 
there is an oil-gland at the root of the tail, the bird with 
his bill presses the oil from it and distributes it over 
his feathers. The Tailor Bird uses it as a needle, and 
partly to its skill are due the beautiful nests of many 
of our small birds. 
The Foot. 
It will be enough to mention a few types to show 
how the anatomy has adapted itself to different modes 
of life. The normal number of toes is four, the fifth 
or “ little toe” having been lost. The first, as a rule, 
points backward. The Emeu, the Rhea, and the 
Cassowary have only three, having lost the first as well. 
The Ostrich has only two, the third and fourth, and the 
latter of these two is small and bears no nail. As in 
the horse, it is the middle toe which carries all the 
weight. Among English birds the most striking 
difference is between the webbed feet of the swimmers 
and the separate-toed feet of the perchers, climbers, 
waders, and runners. The Gannet, the Cormorant, and 
their allies have all four digits connected by the web ; 
in most swimming birds the first is free. There are 
